In addition to these, the next build will also have extensive support for complex IOR, implemented without the need of using external files (though it is of course an option to do so). This is looking pretty interesting, since bella’s material layer component is a true simulation of a thin layer, so it appears that many more IOR files are going to actually be useful, than would be without that.
There was originally a thickness control, but it was redundant, since the transmittance of the layer effectively controls the same thing. That said, Albert had to add thickness control to the complex IOR layer (next build), since in that case we do not control transmittance.
Long story short, you should be able to do lacquer, just play carefully with the layer transmittance. Naturally, the less you transmit through the layer, the less will make it to the conductor/dielectric substrate. Likewise with the layer IOR.